Grass crab spider
This crab spider's eyes sit on small raised bumps, and unlike most spiders it can walk backward and sideways with equal ease while stalking insects on flowers.
| Where | Grass, bushes and flowering plants |
|---|---|
| Size | Female 5.4 to 7.6 mm, male 3.3 to 4.6 mm body length |
| When | April to October |
The Grass crab spider has a short, flattened, fawn to grey-brown body with darker stripes and eyes raised on distinct bumps, quite unlike the rounder, humped shape of many other flower-dwelling crab spiders.
It waits motionless on grass stems, bushes and flowers for flies and other flying insects to come close, then seizes them without building any web. Adults are most easily found through the warmer months of the year.
Traits
Habitat
Grassland
Colour
Brown, Grey, White
Active
Day
To people
Not dangerous to people; it waits motionless on flowers for pollinating insects and poses no threat to anyone nearby.
Activity through the year
Often confused with
Thomisus onustus has a rounded, humped abdomen with two blunt lateral points and can shift colour between pink, white and yellow, unlike the Grass crab spider's flatter, striped body and tubercled eyes.
Questions
Is the Grass crab spider dangerous to people?
Not dangerous to people; it waits motionless on flowers for pollinating insects and poses no threat to anyone nearby.
When can you see the Grass crab spider?
The Grass crab spider can be seen from April to October, by day.
Plate retouched from a photo by Julien Tchilinguirian, CC BY 4.0, iNaturalist Licence
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Last updated 2026-09-27. Every entry is checked against published sources.